1. Field of the Invention
This invention relates to the expansion of tubes in shell and tube heat exchanger tubesheets, and more particularly, to means for actuating and extracting tube guide-expander devices releasably retained in and protruding from the ends of the tubes.
2. Description of the Prior Art
Expanding tubes into contact with tubesheet apertures may be accomplished by the use of rolling tools, hydraulic expanders such as those described in commonly-assigned, allowed application Ser. No. 810,817, filed June 28, 1977, and other conventional means. The hydraulic tube expansion is performable after guiding the tubes into the appropriate tubesheet apertures and removing the tube guides from their ends. Commonly assigned, copending application Ser. No. 898,348, filed Apr. 21, 1978, describes bristled tube guides and apparatus for extracting them from the tubes prior to tube expansion. While removal of such bristled tube guides and subsequent expansion of the enclosing tubes would normally be performed manually by workmen from the inside of a channel head on the primary side of the tubesheet, repair or replacement of tubes in heat exchangers previously subjected to hazardous fluids such as the radioactive environment of nuclear steam generators necessitate minimizing workmen's exposure to the radioactivity.
Removal of the bristled tube guides prior to hydraulic or other tube expansion techniques require positioning the extraction and expansion tools in separate operations on each tube. Positioning and supporting such tools is preferably accomplished by a multi-purpose, remotely operated R.theta. machine as disclosed in commonly-assigned copending application Ser. No. 888,701, filed Mar. 21, 1978. While drastically reducing workmen exposure time to the radioactive environment, use of the aforemented bristled tube guide, extraction apparatus therefor, and hydraulic tube expander require at least one manual tool change for the R.theta. machine. During such tool change, the workman is subjected to radioactive exposure.
To further minimize workmen exposure to radioactivity a dual-duty guide expander was developed and is described in commonly assigned, copending application Ser. No. 955,688 filed Oct. 30, 1978. To effectively utilize such tube guide expander, development of an apparatus for actuating and extracting it from the tube was required.